1. Field of the Invention
The present invention relates to a sintered thin plate member containing a ceramic layer, wherein two or more types of layers, each layer being made of a material having a different thermal expansion coefficient, are laminated.
2. Description of the Related Art
Conventionally, a sintered thin plate member containing a ceramic layer and having two or more types of layers laminated, each of which is made of a material having a different thermal expansion coefficient, has been used for various apparatuses such as a sensor, actuator, unit cell of a solid oxide fuel cell (SOFC), etc. (see Japanese Unexamined Patent Application No. 2004-342584).
The thin plate member used for these apparatuses is extremely thin in order to achieve an object to downsize an apparatus, to reduce an internal electrical resistance and other objects. Therefore, the sintered thin plate member is easily deformed due to an internal stress (thermal stress) caused by the difference in the thermal expansion coefficient between the layers. Further, it may sometimes be deformed due to the occurrence of internal stress (thermal stress) caused by the difference in the shrinkage amount during the sintering. Any deformation of this type of the thin plate member causes various problems.
For example, when this type of the thin plate member is used as a unit cell of an SOFC in which a solid electrolyte layer is used as a ceramic layer, the thin plate member may be deformed when the thickness of the solid electrolyte layer is reduced in order to decrease the internal electrical resistance in the solid electrolyte layer in a cell structure supported by an electrolyte layer. Since a fuel flow path or air flow path formed at the portion opposite to the thin plate member is extremely narrow, a potential problem that the deformed thin plate member might close these flow paths could arise. Even if the thin plate member is deformed to such a degree that does not fully close the flow paths, there arises a problem that the pressure loss may be produced when fluid such as air or fuel flowing through the flow paths increases due to any deformation occurring in the thin plate member.